Integrated circuits find application in many of today's consumer electronics, such as cellphones, video cameras, portable music players, printers, computers, etc. Integrated circuits may include a combination of active devices, passive devices and their interconnections.
A common active device within an integrated circuit is the metal-oxide-semiconductor field-effect transistor (MOSFET), which is commonly referred to as a field-effect transistor (FET). A MOSFET generally includes a semiconductor substrate, having a source, a drain, and a channel located between the source and drain. A gate stack including a conductive material (i.e.—a gate) and an oxide layer (i.e.—a gate oxide) are typically located above the channel. During operation, an inversion layer forms a conducting bridge or “channel” between the source and drain when an appropriate voltage is applied to the gate. Both p-channel and n-channel MOSFET technologies are available and can be combined on a single substrate in one technology, called complementary-metal-oxide-semiconductor or CMOS.
As the semiconductor industry moves towards 45 nanometer node technologies and beyond, there are a few factors that will increase the gain of these MOSFET devices. One such factor is the introduction of strain to the channel of a MOSFET device by forming a strained material adjacent the channel region. In conventional processes, the strained material is formed by an epitaxial process within source/drain extensions and source/drain regions and typically contains a uniform concentration profile (e.g.—for germanium). Unfortunately, these conventional processes fail to maximize the strain inducing effect that different concentration levels for the source/drain extensions and the source/drain regions can have on the channel.
Thus, a need still remains for a reliable integrated circuit system and method of fabrication, wherein the integrated circuit system enhances strain within a channel region by forming source/drain extensions and source/drain regions with different concentration levels. In view of the ever-increasing commercial competitive pressures, increasing consumer expectations, and diminishing opportunities for meaningful product differentiation in the marketplace, it is increasingly critical that answers be found to these problems. Moreover, the ever-increasing need to save costs, improve efficiencies, and meet such competitive pressures adds even greater urgency to the critical necessity that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.